The reason your secondary did not open all the way is that is all the motor wants. Secondary will only open what the motor needs. If you use a 780 CFM carb and the motor can only pull 700 CFM, the secondary will only open so much.
BTW: I do not have check ball in dual quad vacuum secondary Holley tunnel ram setup and does not bog at all. The tires spin so fast it practically put a hole on the black top, and it has 15" of vacuum at idle.

440, .509 cam, single plane,727 hi stall, 4.10 gear, hoosier DOT. It was a lot of fun. I followed the reciepe on the box. The jobber connection parts had formulas on the back for bracket racing. So I built the 13 second car, and it ran 13 seconds . Go figure.

If you drill a big hole in the manifold, your carbs secondary, or the carb for that matter is not going to pull fuel. So manifold vacuum is the signal that makes the carb function. Or the negative pressure underneath the carb to simplify it even more.

I think you are having a problem because of a comment I made about my engine. That I had described the idle with a unit of vacuum and where I measured this.

I have worked with carbs for years of all types. To say that it would have opened all the way racing, and NOT stumbled at cruise, is a bold statement.

The port for the pod is at the venturi. Of coarse , that is the best place to get a signal for the pod.

To say that the vacuum underneath the carb don't have anything to do with operation, now said twice, is not believeable.

Neither. If you have a GM hei, info on limiting the mechanical advance, as well as timing info in general, is here.

Quote:

To b honest I have no Idea do I plug a vacuum gauge to the carb??? All I kno it's a enough to keep vacuum brakes and power steering

To check the vacuum, connect a vacuum gauge to a FULL TIME vacuum source, also called "manifold" vacuum. A manifold vacuum source can be located on the carb (on the baseplate of a Holley), OR from a port located on the runner of the intake manifold.

The 'other' type of vacuum signal is called "ported" vacuum. Ported vacuum is absent (or nearly so, depending on how far the primary throttle blades are opened to set the idle speed) w/the throttle blades closed because of where the vacuum orifice is located in the carb (above the throttle plates), and will only be present when the throttle blades are opened to some degree. On a Holley, ported vacuum port is the one located on the metering block.

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